JP5993671B2 - LED luminous flux control device, road lighting device - Google Patents

Description

  The present invention relates to an LED light flux control device and a road illumination device that light an LED with a constant light flux (brightness).

  2. Description of the Related Art In recent years, an LED (light emitting diode) is employed as a light source in a road lighting device or the like that is installed at an upper portion of a support column that stands on the side of a road and illuminates a road below.

  As a technique for controlling the luminous flux (brightness) of the LED, there is a technique for measuring the luminous flux with an optical sensor and controlling it to a target luminous flux.

  Further, since the luminous flux of the LED greatly depends on the temperature (particularly the junction temperature), the ambient temperature of the LED is measured by a temperature sensor, and the luminous flux is estimated from the ambient temperature and controlled.

  In addition, an LED driving circuit has been devised in which an operational amplifier for driving an LED is fed back with a forward voltage of the LED to suppress a change in light flux depending on temperature (see Patent Document 1).

Patent No. 3000667

  In the method using an optical sensor or a temperature sensor, the cost increases as much as the sensor is provided. In particular, in an illuminating device using a plurality of light source modules, it is necessary to provide a sensor for each light source module, which increases the cost.

  On the other hand, although the LED drive circuit disclosed in Patent Document 1 can suppress the fluctuation of the luminous flux depending on the temperature to some extent, it is not sufficient.

  In particular, in the road lighting device, the heat capacity of the housing is large, and since it takes a relatively long time for the temperature to rise and stabilize after the power is turned on, it is required to suppress fluctuations in brightness during that time.

  The present invention is intended to solve the above-described problem, and an LED light flux control device and a road that can control the light flux emitted from an LED uniformly with high accuracy without using a sensor such as an optical sensor or a temperature sensor. The object is to provide a lighting device.

  The gist of the present invention for achieving the object lies in the inventions of the following items.

[1] a driving source for driving the light emitting diode at a constant current;
A measuring unit for measuring a forward voltage of the light emitting diode;
A storage unit storing an elapsed time versus temperature characteristic indicating a relationship between an elapsed time after power-on in a predetermined lighting device using the light emitting diode as a light source and an ambient temperature of the light emitting diode;
A control unit that controls a driving state of the light emitting diode by the driving source so that a light flux emitted from the light emitting diode becomes a predetermined target value;
The controller is
When the lighting device is turned on,
The forward voltage of the light emitting diode is measured by the measuring unit, and the ambient temperature corresponding to the measured forward voltage is obtained from the known relationship between the ambient temperature of the light emitting diode and the forward voltage, and the ambient temperature is calculated. Performing an initial operation to obtain the elapsed time vs. temperature characteristics when the initial temperature is set based on the storage content of the storage unit,
After that,
The known ambient temperature of the light emitting diode is obtained from the elapsed time from power-on to the present and the elapsed time vs. temperature characteristic obtained in the initial operation, and the relationship between the ambient temperature and the luminous flux emitted from the light emitting diode is shown. The value of the luminous flux emitted by the light emitting diode with respect to the current ambient temperature is obtained from the ambient temperature versus luminous flux characteristics of the light source, and the driving state of the light emitting diode by the drive source is determined so that the luminous flux emitted by the light emitting diode becomes a target value. An LED light flux control device characterized in that the first control is repeatedly performed.

  In the above invention, the elapsed time versus temperature characteristic indicating the relationship between the elapsed time after power-on and the ambient temperature of the light emitting diode is stored in advance. Next, the ambient temperature when the power is turned on is obtained from the forward voltage of the LED measured when the power is turned on. Then, an elapsed time vs. temperature characteristic when this ambient temperature is set as the initial temperature is obtained based on the characteristic stored in the storage unit (for example, by correction). Thereafter, the current ambient temperature is obtained from the elapsed time vs. temperature characteristic and the elapsed time from the power-on, and the current luminous flux is obtained from a known characteristic indicating the relationship between the ambient temperature and the luminous flux and the current ambient temperature, By repeatedly performing control so that the emitted light beam becomes the target value, the light beam is made constant at the target value.

[2] The elapsed time versus temperature characteristic when the reference temperature is set as the initial temperature is stored in the storage unit,
The control unit corrects the elapsed time versus temperature characteristic stored in the storage unit based on a difference between the ambient temperature at power-on and the reference temperature, thereby changing the ambient temperature at power-on to an initial temperature. The LED light flux control device according to [1], wherein the elapsed time vs. temperature characteristic is obtained.

  In the above invention, the elapsed time vs. temperature characteristic with respect to the reference temperature is corrected based on the difference between the ambient temperature when the power is turned on and the reference temperature, so that the elapsed time vs. temperature characteristic using the ambient temperature when the power is turned on as the initial temperature. To get.

[3] The control unit
Measure the cumulative lighting time of the light emitting diode,
From the known characteristics indicating the relationship between the cumulative lighting time of the light emitting diode and the luminous flux decay rate, the luminous flux decay rate for the current cumulative lighting time is determined,
The LED light flux control apparatus according to [1] or [2], wherein the first control is performed so that a light flux emitted from the light emitting diode becomes the target value including attenuation at the light flux attenuation rate. .

  In the above-described invention, the light beam attenuation caused by the cumulative lighting time is further compensated.

[4] After the ambient temperature of the light emitting diode has stabilized, the control unit determines that the increase in the accumulated lighting time is a factor of fluctuation of the light flux, and causes the light flux emitted from the light emitting diode to reach the target value. The LED light flux control device according to [3], wherein the second control for controlling the driving state of the light emitting diode by the source is repeatedly performed.

  In the above invention, after the ambient temperature is stabilized, there is no fluctuation of the luminous flux depending on the ambient temperature. Therefore, it is assumed that the subsequent fluctuation factor of the luminous flux is an increase in the cumulative lighting time, and the control is performed to maintain the luminous flux at the target value. .

[5] The control unit periodically measures the forward voltage of the light emitting diode by the measurement unit after the ambient temperature of the light emitting diode is stabilized, and the measured value changes beyond the normal range. The LED light flux control apparatus according to any one of [1] to [4], wherein a failure of the light emitting diode is detected.

  In the above invention, if the forward voltage of the LED changes greatly after the ambient temperature has stabilized, it is determined that a failure has occurred in the LED.

[6] The LED light flux control device according to [5], wherein the periodic measurement period is longer than the execution period of the first control.

  In the said invention, the measurement for failure detection performed after ambient temperature is stabilized is performed with a period longer than the execution period of 1st control. For example, the first control is about 10 ms and the measurement cycle is 1 second.

[7] While driving a plurality of light emitting diodes,
[5] or [6], wherein when the control unit detects a failure of some of the light emitting diodes, the control unit strengthens the luminous flux of the remaining normal light emitting diodes to compensate for the reduction of the luminous flux due to the failure. The LED light flux control device described.

  In the above invention, for example, when some of the plurality of light emitting diodes are short-circuited, the luminous flux of other normal light emitting diodes is strengthened to compensate for the decrease in the luminous flux as a whole.

[8] A road lighting device for lighting a road from above,
A housing having an irradiation port covered with a light-transmitting plate;
A plurality of light emitting diodes housed in the housing;
The LED light flux control device according to any one of [1] to [7], which drives the plurality of light emitting diodes;
A road lighting device characterized by comprising:

  In the above invention, the brightness of the road lighting device is always controlled to be constant after the power is turned on.

[9] A plurality of light emitting modules in which a plurality of light emitting diodes are arranged,
The road according to [8], wherein the LED light flux control device controls to compensate for a decrease in brightness caused by a failure in one light emitting module by increasing the brightness of another light emitting module. Lighting device.

  In the above-described invention, when a failure (for example, an open failure) occurs in any one of the light emitting modules, the decrease in the luminous flux due to the failure is compensated by increasing the brightness of the other light emitting modules.

  According to the LED light beam control device and the road lighting device according to the present invention, the light beam emitted from the LED can be controlled to be constant with high accuracy without using a sensor such as an optical sensor or a temperature sensor.

It is a block diagram which shows the structure of the LED light beam control apparatus which concerns on embodiment of this invention. It is a figure which shows the characteristic of elapsed time-ambient temperature. It is a flowchart which shows the process which CPU of a LED light beam control apparatus performs. FIG. 4 is a flowchart showing a continuation of FIG. 3. It is a figure which shows the characteristic of ambient temperature-forward voltage. It is a figure which shows the characteristic of ambient temperature-relative light beam. It is a figure which shows the characteristic of elapsed time-relative light beam. It is a figure which shows the characteristic of elapsed time-luminous flux attenuation factor. It is a figure which shows the example of installation of the road illuminating device which concerns on embodiment of this invention. 1 is a perspective view showing a road lighting device according to an embodiment of the present invention. It is a figure which shows the front of the road illuminating device which concerns on embodiment of this invention, a lower surface, an upper surface, a back surface, and a side surface. It is a figure which shows the inside (array of a light emitting module) of the road lighting apparatus which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a circuit configuration of an LED light flux control device 10 according to an embodiment of the present invention. The LED light flux control device 10 functions to drive these light source portions 5 so that the light flux emitted from the plurality of light source portions 5 to be driven is kept at a predetermined target value. Each light source unit 5 includes a plurality of light emitting diodes (hereinafter referred to as LEDs) connected in series.

  The LED luminous flux control device 10 includes a drive unit 11 for driving the light source unit 5 including an LED to which a lens for controlling light distribution is attached, a control unit 13 for outputting a control signal 12 to the drive unit 11, A power supply unit 18 that supplies power to the drive unit 11 and the control unit 13 is provided.

  The drive unit 11 includes a constant current circuit and a switching transistor that turns on and off the power supply from the constant current circuit to the light source unit 5 for each light source unit 5. Here, the drive unit 11 drives the light source unit 5 by a PWM (Pulse Width Modulation) method.

  The control unit 13 includes an A / D (analog to digital) converter 14, a CPU (Central Processing Unit) 15, and a storage unit 16, and the output of the A / D converter 14 and the storage unit 16 are connected to the CPU 15. ing. In addition, a ROM (Read Only Memory) in which a program executed by the CPU 15 is stored, a RAM (Random Access Memory) as a work memory for temporarily storing various data when the CPU 15 executes processing, and the like are provided. Yes.

  The A / D converter 14 has inputs of a plurality of channels, and one channel is assigned to each light source unit 5. The voltage between both ends of the corresponding light source unit 5 is input to each channel. This voltage corresponds to the total forward voltage of a plurality of LEDs in series that constitute the light source unit 5. The A / D converter 14 converts the input voltage of each channel into a digital value and outputs it.

  The storage unit 16 stores a characteristic (elapsed time vs. temperature characteristic) indicating a relationship between an elapsed time after power-on and an ambient temperature of the light source unit 5 in a predetermined lighting device using the light source unit 5 as a light source. . Here, the elapsed time versus temperature characteristic when the initial temperature at power-on is 25 ° C. is stored as the reference temperature carp. FIG. 2 shows an example of the reference temperature curve.

  The CPU 15 outputs a control signal 12 to the drive unit 11 so that the light flux emitted from each light source unit 5 becomes a predetermined target value. The control signal 12 is a PWM signal for each light source unit 5.

  Next, control for maintaining the light flux output from the light source unit 5 at a predetermined target value will be described.

  3 and 4 show the flow of control performed immediately after the LED light flux controller 10 is turned on. CPU15 measures the forward voltage of LED which comprises the light source part 5 at the time of power-on (at the time of lighting start) (step S101). Specifically, the forward voltage of each light source unit 5 is captured by the A / D converter 14 immediately after the drive unit 11 starts driving the light source unit 5. Here, the number of a plurality of LEDs connected in series constituting the light source unit 5 is represented by M. The CPU 15 obtains a value obtained by dividing the voltage value Vfa acquired from the A / D converter 14 by M as a forward voltage Vf per LED. In addition, the drive part 11 shall drive the light source part 5 by constant current at 700 mA.

  It is known that the ambient temperature of the LED and the forward voltage have a relationship as shown in FIG. This characteristic is a characteristic when the LED is driven with the same driving current of 700 mA as when the driving unit 11 drives the light source unit 5. The CPU 15 estimates the ambient temperature when the power is turned on from the forward voltage Vf measured when the power is turned on and the characteristics shown in FIG. 2 (step S102). The estimation of the ambient temperature may be obtained by making a table of “ambient temperature-forward voltage characteristics” shown in FIG. 2 and registering it with reference to this table or by using an approximate expression. .

  Immediately after starting the driving of the light source unit 5 when the power is turned on, an increase in Tj (junction temperature) due to heat generation of the LEDs constituting the light source unit 5 can be almost ignored by instantaneously taking in the forward voltage. The temperature Ta≈Tj. Therefore, the ambient temperature Ta can be accurately estimated by measuring Vf when the power is turned on.

  Next, the CPU 15 obtains a temperature difference ΔT between the estimated ambient temperature Ta and a reference temperature (25 ° C.). Then, ΔT is added to the reference temperature curve previously recorded in the storage unit 16 to correct it, thereby obtaining a temperature curve under the operating environment (step S103). The corrected temperature curve has a characteristic in which the reference temperature curve is translated in the vertical direction by the temperature difference ΔT.

  The operation so far is the initial operation when the power is turned on, and thereafter, the light flux is controlled to be constant using the temperature curve obtained in the initial operation.

  The CPU 15 measures an elapsed time (lighting time) since the power is turned on (step S104). Then, an ambient temperature (current ambient temperature) corresponding to the current elapsed time is obtained from the temperature curve obtained in step S103 (step S105).

  Next, the value of the relative luminous flux corresponding to the current ambient temperature obtained in step S105 is obtained from the known characteristic indicating the relationship between the ambient temperature and the relative luminous flux (step S106). This is an estimate of the current relative luminous flux. FIG. 6 is a graph showing the relationship between the ambient temperature and the relative luminous flux when the drive current If is 700 mA. The relative luminous flux represents the luminous flux as a relative value when a predetermined luminous flux value is 1.

  FIG. 7 shows the elapsed time-relative light flux characteristics obtained from the temperature curve and the ambient temperature-relative light flux characteristics of FIG. The characteristic shown in FIG. 7 may be obtained in step S103, and thereafter, the relative luminous flux (the estimated value of the current relative luminous flux) corresponding to the elapsed time from the power-on to the present may be obtained from the characteristic shown in FIG.

Next, a first correction value C at which the relative light flux becomes a target value (however, the light flux attenuation due to the cumulative lighting time is not included) is obtained (step S107). When the relative luminous flux value (target value) is φ _g and the current relative luminous flux estimate is φ when a sufficient time has passed since the power was turned on and the ambient temperature is stable,
First correction value C = φ _g / φ (1)

  Next, the attenuation of the light beam according to the cumulative lighting time is compensated. The characteristic of the luminous flux attenuation rate with respect to the cumulative lighting time is known and stored in the storage unit 16. FIG. 8 shows an example of the characteristics of the luminous flux attenuation rate with respect to the cumulative lighting time.

  The CPU 15 measures the cumulative lighting time, and reads the luminous flux attenuation rate corresponding to the current cumulative lighting time from the aforementioned characteristics stored in the storage unit 16 (step S108).

The CPU 15 obtains the dimming rate R so that the relative luminous flux becomes the target value including the luminous flux attenuation due to the cumulative lighting time (step S109). If the luminous flux decay rate corresponding to the current cumulative lighting time is D,
Dimming rate R = first correction value C × D (2)

  Next, the CPU 15 determines whether or not the increase in the ambient temperature of the light source unit 5 has stopped and the ambient temperature has entered a stable state (step S110). Here, when the elapsed time from power-on exceeds a predetermined reference time, it is determined that the ambient temperature has entered a stable state. The reference time is set in advance from the graph of FIG. For example, it is set to 3 hours.

  Before the ambient temperature becomes stable (step S110; No), the control signal 12 is set so that the light source unit 5 is driven at the dimming rate R calculated in step S109. Specifically, the duty ratio of the PWM signal output to the drive unit 11 is set to the dimming rate R, and the PWM signal having the duty ratio is output to the drive unit 11. The processing of steps S104 to S111 is executed with a sufficiently short cycle (for example, several ms to several tens of ms).

  When the ambient temperature becomes stable (step S110; Yes), the control signal 12 is set so that the light source unit 5 is driven at the calculated dimming rate R (step S201). Further, the value of the first correction value C obtained immediately before is stored.

  After the ambient temperature becomes stable, the value of the first correction value C does not change with the value when the ambient temperature shifts to the stable state. Accordingly, the subsequent dimming rate R may be changed depending only on the luminous flux attenuation rate depending on the cumulative lighting time.

  The CPU 15 calculates the cumulative lighting time (step S202), and acquires the luminous flux attenuation rate with respect to the current cumulative lighting time from the characteristics of the luminous flux decay rate with respect to the cumulative lighting time stored in the storage unit 16 (step S203). The dimming rate R is calculated by substituting the luminous flux attenuation rate D and the stored first correction value C when the stable state is entered into the equation (2) (step S204).

  Next, the current forward voltage Vfa of the light source unit 5 (the forward voltage in units of the light source unit 5 in which a plurality of LEDs are connected in series) is measured (step S205) and compared with the past Vfa ( Step S206) When a sudden change (for example, 3 V or more) is detected, it is determined that a failure such as a broken ball (step S207; Yes).

  If no failure is detected (step S207; No), the forward voltage Vfa measured this time is stored (step S208), and the process returns to step S201 and continues. Note that the execution cycle of the processes in steps S201 to S208 is sufficiently longer than the cycle of the processes in steps S104 to S111. For example, the period is from 1 second to several seconds.

  When a failure is detected (step S207; Yes), an error signal such as a broken ball is output (step S209). Then, the dimming rate at the time of driving the remaining normal LEDs is reset so as to compensate for the decrease in the luminous flux caused by the failure (step S210).

For example, when the forward voltage of one LED is 3.0V, an open failure is determined if the difference between the current Vfa and the previous Vfa is 3.0V or more. If the difference between the current Vfa and the previous Vfa is −3.0 V or less, it is determined that a short circuit failure has occurred. That is,
Vfa− _{Vfa_OLD} ≧ 3.0V... Open failure Vfa− _{Vfa_OLD} ≦ −3.0V.

  Thereby, normal LED can be dimmed and an appropriate light beam can be maintained. For example, in the case where 14 LEDs are connected in series in one light source unit 5, if Vfa corresponding to a certain light source unit 5 is 9 V lower than a normal value, it is determined that three LEDs have failed. At this time, the remaining eleven normal LEDs and / or the light beams of the other light source units 5 are raised to compensate for the decrease of the light beam due to the failure. If Vfa is higher than the normal value by 3 V or more, it is determined that the LED has an open failure. In this case, since all the LEDs of the light source unit 5 in which the open failure has occurred are not lit, the luminous flux of another normal light source unit 5 is raised to compensate for the decrease in the luminous flux due to the failure.

  As described above, the LED light flux control device 10 repeatedly performs the control shown in FIGS. 3 and 4, so that the light flux emitted from the illumination device using the plurality of light source units 5 as the light source is always a constant value (target value). Control to be. As a result, the luminous flux can be kept constant in response to all factors such as changes in ambient temperature due to heat generation after power-on, deterioration due to increase in cumulative lighting time, and failure.

  The forward voltage of the LED is used to estimate the initial ambient temperature when the power is turned on, and thereafter, the luminous flux is controlled based on the temperature curve. Therefore, it is necessary to measure a subtle change in the forward voltage. Absent. Further, it is sufficient to detect a sudden change of 3 V or more in detecting a failure. Therefore, even if the forward voltage of the light source unit 5 is directly input to the A / D converter 14, sufficient measurement accuracy can be secured, so there is no need to provide a differential circuit or an amplifier circuit in the circuit for measuring the forward voltage. The circuit configuration is simplified.

  The measurement of the forward voltage only needs to be performed in a long cycle for detecting a failure when the power is turned on and after the ambient temperature is stabilized, so that the processing load on the CPU 15 related to the forward voltage monitoring process is reduced. For example, energy saving can be achieved by reducing the operating rate of the CPU.

  FIG. 9 shows an installation example of the road lighting device 60 using the LED light flux control device 10. The road illumination device 60 is attached to an upper portion of a support column 53 that is erected on the side of the road 52, and illuminates the road 52 and its surroundings from above. The road lighting device 60 is installed at intervals of several tens of meters (for example, 40 m) along the longitudinal direction of the road. In each figure, the arrow L indicates the longitudinal direction (longitudinal direction) of the road 52, and the arrow W indicates the width direction (transverse direction) of the road 52.

  FIG. 10 is a perspective view of the road illumination device 60 as viewed obliquely from above and front. FIG. 11 shows the front, bottom, top, back, and side of the road lighting device 60. The road lighting device 60 includes a housing 61 having a light irradiation port on the lower surface side, a plurality of light emitting modules 70 (see FIG. 12) housed in the housing 61, and LED light fluxes that drive the light emitting modules 70. It is comprised by the control apparatus 10 grade | etc.,. One light emitting module 70 corresponds to one light source unit 5 in FIG.

  The main part of the housing 61 is a cast product manufactured by pouring molten metal into a mold, cooling and solidifying it. For this reason, the heat capacity is large, and it takes a relatively long time from when the power is turned on (lighting starts) until the temperature reaches a stable state. Since the reference temperature curve stored in the storage unit 16 varies depending on the heat capacity of the casing 61 and the number of light emitting modules 70 attached, the reference temperature curve is stored for each road lighting device 60 or for each configuration specification of the road lighting device 60. Measured and stored.

  A housing 61 of the road lighting device 60 extends forward from the base 62 and a base 62 that houses a metal fitting for fixing the road lighting device 60 to the support 53 and the LED light flux control device 10 that drives the light emitting module 70. In addition, the main body 64 is formed of a horizontally long, substantially rectangular and relatively thin hollow box.

  A substantially rectangular irradiation port 66 is opened on the lower surface of the main body 64. A translucent plate 68 is fitted into the irradiation port 66 with a packing interposed therebetween. The translucent plate 68 is a plate-like member that transmits light, and is made of glass, resin, or the like.

  FIG. 12 shows a state in which the road lighting device 60 with the translucent plate 68 removed is viewed from the lower surface side. A plurality of light emitting modules 70 are accommodated in the main body portion 64 so as to face the irradiation port 66 from the inside of the main body portion 64.

  The light emitting module 70 is configured by arranging a plurality of LEDs 6 on a flat substrate and covering each LED 6 with a lens 75. Here, 14 LEDs 6 covered with lenses 75 are arranged in a 2 × 7 matrix on a rectangular substrate. The plurality of LEDs 6 in each light emitting module 70 are connected in series. In the main body 64, the six light emitting modules 70 are arranged in a 3 × 2 matrix and attached. Note that the number of light emitting modules 70 attached can be increased or decreased.

  In the road lighting device 60, the casing 61 is manufactured by casting, and the heat capacity is large. For this reason, it takes a relatively long time for the temperature rise from the start of lighting to stabilize. Therefore, when the light flux stabilization control is not performed by the LED light flux control device 10, the brightness varies over a relatively long time so that the brightness becomes brighter than the target immediately after the start of lighting and gradually becomes darker as the temperature rises.

  However, since the road illumination device 60 is controlled to make the luminous flux constant by the LED luminous flux control device 10, it can maintain the target brightness immediately after the start of lighting.

  Further, when a short circuit failure of the LED 6 occurs in any one of the light emitting modules 70, the LED light flux control device 10 is normal in the light emitting module 70 in which the failure occurs so as to compensate for the decrease in brightness due to the short circuit failure. The other LEDs 6 are controlled to increase the brightness. Alternatively, the brightness of both the light emitting module 70 in which the short failure has occurred and the other light emitting modules 70 are adjusted to compensate for the decrease in the luminous flux due to the failure.

  When an open failure is detected, the entire light emitting module 70 in which the failure has occurred does not emit light. Therefore, the LED light flux control device 10 uses the brightness of the other light emitting modules 70 to compensate for a decrease in brightness due to the failure. Control to make it brighter than usual. For example, when one of the six light emitting modules 70 has an open failure, the brightness of the other five normal light emitting modules 70 is controlled to increase by 20%.

  The embodiment of the present invention has been described with reference to the drawings. However, the specific configuration is not limited to that shown in the embodiment, and there are changes and additions within the scope of the present invention. Are also included in the present invention.

  For example, in the embodiment, the brightness is controlled by the PWM method, but the control method is not limited to this.

  In the embodiment, the reference temperature curve is corrected according to the ambient temperature when the power is turned on, and the temperature curve under the operating environment is acquired. For example, the storage unit 16 stores the temperature curve for each ambient temperature when the power is turned on. A large number of temperature curves may be stored, and a temperature curve corresponding to the ambient temperature when the power is turned on may be selected.

  In the embodiment, an example is shown in which a failure is detected and control is performed so as to compensate for brightness. However, the failure detection is automatically notified to, for example, a management office that manages the road lighting device 60 via a network. May be configured.

5 ... Light source 6 ... LED
DESCRIPTION OF SYMBOLS 10 ... LED light beam control apparatus 11 ... Drive part 12 ... Control signal 13 ... Control part 14 ... A / D converter 15 ... CPU
DESCRIPTION OF SYMBOLS 16 ... Memory | storage part 18 ... Power supply part 52 ... Road 53 ... Support | pillar 60 ... Road illuminating device 61 ... Housing 62 ... Base part 64 ... Main body part 66 ... Irradiation port 68 ... Translucent plate 70 ... Light emitting module 75 ... Lens

Claims (9)

A driving source for driving the light emitting diode at a constant current;
A measuring unit for measuring a forward voltage of the light emitting diode;
A storage unit storing an elapsed time versus temperature characteristic indicating a relationship between an elapsed time after power-on in a predetermined lighting device using the light emitting diode as a light source and an ambient temperature of the light emitting diode;
A control unit that controls a driving state of the light emitting diode by the driving source so that a light flux emitted from the light emitting diode becomes a predetermined target value;
The controller is
When the lighting device is turned on,
The forward voltage of the light emitting diode is measured by the measuring unit, and the ambient temperature corresponding to the measured forward voltage is obtained from the known relationship between the ambient temperature of the light emitting diode and the forward voltage, and the ambient temperature is calculated. Performing an initial operation to obtain the elapsed time vs. temperature characteristics when the initial temperature is set based on the storage content of the storage unit,
After that,
The known ambient temperature of the light emitting diode is obtained from the elapsed time from power-on to the present and the elapsed time vs. temperature characteristic obtained in the initial operation, and the relationship between the ambient temperature and the luminous flux emitted from the light emitting diode is shown. The value of the luminous flux emitted by the light emitting diode with respect to the current ambient temperature is obtained from the ambient temperature versus luminous flux characteristics of the light source, and the driving state of the light emitting diode by the drive source is determined so that the luminous flux emitted by the light emitting diode becomes a target value. An LED light flux control device characterized in that the first control is repeatedly performed. In the storage unit, the elapsed time versus temperature characteristic when the reference temperature is set as the initial temperature is stored,
The control unit corrects the elapsed time versus temperature characteristic stored in the storage unit based on a difference between the ambient temperature at power-on and the reference temperature, thereby changing the ambient temperature at power-on to an initial temperature. The LED light flux control device according to claim 1, wherein the elapsed time versus temperature characteristic is obtained. The controller is
Measure the cumulative lighting time of the light emitting diode,
From the known characteristics indicating the relationship between the cumulative lighting time of the light emitting diode and the luminous flux decay rate, the luminous flux decay rate for the current cumulative lighting time is determined,
3. The LED light flux control apparatus according to claim 1, wherein the first control is performed so that a light flux emitted from the light emitting diode becomes the target value including attenuation at the light flux attenuation rate. After the ambient temperature of the light emitting diode has stabilized, the control unit determines that the increase in the cumulative lighting time is a factor of fluctuation of the light beam, and the light source emitted from the light emitting diode becomes the target value so that the light source emits the target value. The LED light flux control device according to claim 3, wherein the second control for controlling the driving state of the light emitting diode is repeatedly performed. After the ambient temperature of the light emitting diode is stabilized, the control unit periodically measures the forward voltage of the light emitting diode by the measuring unit, and when the measured value changes beyond a normal range, the light emitting diode The LED light flux control device according to any one of claims 1 to 4, wherein a failure of the LED is detected. The LED light flux control device according to claim 5, wherein the periodic measurement period is longer than the execution period of the first control. Driving multiple light emitting diodes,
The said control part strengthens the light beam of the remaining normal light emitting diode, and compensates for the fall of the light beam by the said failure, when the failure of some light emitting diodes is detected. LED luminous flux control device. A road lighting device that illuminates a road from above,
A housing having an irradiation port covered with a light-transmitting plate;
A plurality of light emitting diodes housed in the housing;
The LED light flux control device according to any one of claims 1 to 7, which drives the plurality of light emitting diodes;
A road lighting device characterized by comprising: A plurality of light emitting modules in which a plurality of light emitting diodes are arranged,
9. The road according to claim 8, wherein the LED light flux control device performs control to compensate for a decrease in brightness caused by a failure occurring in one light emitting module by increasing the brightness of another light emitting module. Lighting device.